A CDN is a layer of an intelligent virtual network that includes node servers disposed throughout a network and that is based on the existing Internet. According to comprehensive information such as network traffic, a connection and a load status of each node, a distance between each node and a user, and a response time, the CDN may redirect in real time a user's request to a serving node closest to the user such that a node closer to a user is selected to send content required by the user to the user, a network congestion status is mitigated, and a response speed of a website is improved.
A CDN-based access control method provided in the other approaches is as follows.
When a user accesses a content resource of a service server using a user agent (such as, a browser, a download tool, or a streaming media player), the service server generates a uniform resource locator (URL) according to an algorithm and a key provided by a CDN server. The URL points to a content resource in the CDN server, the user accesses the content resource in the CDN server using the URL, and the CDN server sends a content resource requested by the user to the user.
However, if an intruder cracks the URL obtained using the user agent, the intruder may obtain an actual address of the content resource. The intruder may bypass the service server and obtain the content resource using the actual address. Therefore, there is a risk in a content resource stored in the CDN server.